1. Field of the Invention
The present invention relates to a breathing assistance apparatus for treating sleep apnoea. More specifically, the present invention provides nasal interface for the supply of respiratory gases, but most particularly positive pressure gases.
The invention also relates to a patient interface which includes nasal pillows, or nasal plugs and which may also include associated elements such as headgear.
2. Description of the Related Art
Obstructive Sleep Apnoea (OSA) is a sleep disorder that affects up to at least 5% of the population in which muscles that normally hold the airway open relax and ultimately collapse, sealing the airway. The sleep pattern of an OSA sufferer is characterised by repeated sequences of snoring, breathing difficulty, lack of breathing, waking with a start and then returning to sleep. Often the sufferer is unaware of this pattern occurring. Sufferers of OSA usually experience daytime drowsiness and irritability due to a lack of good continuous sleep.
In an effort to treat OSA sufferers, a technique known as Continuous Positive Airway Pressure (CPAP) was devised. A CPAP device consists of a gases supply (or blower) with a conduit connected to supply pressurised gases to a patient, usually through a mask, nasal prongs, plugs or pillows. The pressurised air supplied to the patient effectively assists the muscles to keep the patient's airway open, eliminating the typical OSA sleep pattern.
The procedure for administering CPAP treatment has been well documented in both the technical and patent literature. Briefly stated, CPAP treatment acts as a pneumatic splint of the airway by the provision of a positive pressure, usually in the range 4 to 20 cm H2O. The air is supplied to the airway by a motor driven blower whose outlet passes via an air delivery hose to a nose (or nose and/or mouth) mask sealingly engaged to a patient's face by means of a harness or other headgear.
It is known to provide a flow of respiratory gases to a user via a nasal cannula to relieve a number of ailments, for example, sleep apnoea or snoring. One problem with supplying a flow of gases to a user via an interface such as a nasal interface, prongs or plugs (“nasal interface”) is that it can be difficult to form a good seal between the nasal interface and the user's nostrils. The nasal interface is often held in place against the user's nose by headgear worn on the user's head. The head gear may be over tightened so that the nasal interface is pressed uncomfortably onto the user's nose. Alternatively the headgear may be applied to the user's head too loosely, preventing an effective seal being formed between the interface and user's nostrils. Also, the seal between the interface and the user's nostrils may be broken if the interface is knocked while the user sleeps, or if the user moves while sleeping.
There are a number of different mechanisms which are known in the art which are intended to offer a solution to this problem.
U.S. Pat. No. 4,782,832 describes a nasal puff assembly with a pair of bellows type corrugated nare elements designed to sit adjacent to and partially within the nose of the user. The assembly includes a hollow plenum to which the pair of nare elements are operationally connected. The plenum is configured to allow the nare elements to rotate and also shift laterally in order to custom fit the assembly to a wide variety of users.
US 2006/0107958 describes an adjustable ventilation interface including a nasal cannula body. The cannula body has a pair of nasal prongs that are adjustable with respect to each other. The nasal prongs are located on the top portion of the nasal cannula body to create a sealing interface with a user's nose. The cannula body has first and second bellows-like structures. The first bellows like structure provides adjustability in a centre-to-centre distance between the nasal prongs. The second bellows-like structure creates a sealing engagement with a bottom area of the user's nose. The nasal prongs have thin corrugated walls that are designed to inflate under pressure. In a compressed or folded state the prongs can be easily inserted into a user's nose. In an inflated state the prongs assume a barrel-shaped structure to provide a large, even sealing surface in the flares. The prongs are folded or corrugated when not in use, so that their outer perimeter or profile is smaller than when they are inflated. This allows them to be easily inserted into the user's nostrils. In use the prongs inflate and seal against the user's nostrils. Because the inner surface of the user's nostrils is smooth, in use when the gas is flowing through the prongs, the prongs will inflate and have a smooth outer surface.
U.S. Pat. No. 6,431,172 describes a nasal cannula with an inflatable plenum chamber mounted on a rigid support. A pair of nares elements are mounted on the inflatable plenum chamber for insertion into the nostrils of the user. The inflatable plenum chamber is flaccid when not pressurised and not effective in transmitting forces between nares elements and the rigid support. When inflated the inflatable plenum acts to absorb shocks and jolts without transmitting the shocks and jolts to the user. The inflatable plenum provides additional degrees of freedom for movement of the nares elements while at the same time increasing the range of movement in all directions to accommodate large physical differences between users. For example each nares element can move axially, laterally, rotate and tilt.
The prior art further includes a nasal pillows interface in which headgear retains a soft plenum in the vicinity of the user's nose. A pair of flexible protrusions engage against the nares of the recipient. Typically, the protrusions are able to axially compress and have a lateral freedom of movement relative to the supporting cushion. Examples are the ResMed Mirage Swift™ II, or the Fisher and Paykel Opus™ 360 interfaces or nasal masks. A variety of different pillow configurations which could be used with these interfaces are described and shown in WO 2008/014543 and US 2009/044808.
The prior art still further includes a nasal cannula interface. The nasal canal interface includes a plenum portion that rests against the upper lip of the user and a pair of prongs. Each prong extends into the nostril of the user. An example is the Nasal-Aire interface made by Innomed, where gases are provided to the interface and the prongs by conduits or hoses that extend from the users nose across their cheeks, over their ears and around the back of their head.
Interfaces such as those described above are frequently used for delivering pressurised gases to a person being treated for obstructive sleep apnea (OSA) or other sleep disorders. These users typically wear the interface in a home sleeping environment. Comfort and effective sealing even under conditions of patient movement are major considerations.
In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.
The term “comprising” as used in this specification means “consisting at least in part of”. When interpreting each statement in this specification that includes the term “comprising”, features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and “comprises” are to be interpreted in the same manner.